code changes made while bug fixing

Could see that initalisation message was being sent as part of the
ExtTemp string.   Had increased buffer size and changed string position
to try to determine issue.  Issue was due to alt long somehow.  When
changed (in RTSHABC) back to an int this issue stopped occuring.
RTSHABC

Removed External Temp and changed alt back to an int to correct errors
in code.
Corrected code error

Needed to amend checksum calculation string due to extra $$ being
transmitted in data string